Intital timing at 35, WHY? - Team Camaro Tech
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post #1 of 3 (permalink) Old Oct 27th, 03, 07:50 AM Thread Starter
Join Date: Feb 2003
Posts: 17

The patient is a 69 Z28 with 302 and solid lifter cam. A few months ago I changed out intakes for an orginal Z28 manifold. I did not check initial timing before the removal. After it was back together with timing set at 6 to 14 the car only had about 5-7 lbs of vacuum which was not enough to operate the power brakes. Before the switch the brakes worked fine. I have reset initial timing with a vaccuum gauge and the highest vaccuum is about 12-14 lbs at timing setting of about 30 to 35. The car seems to run fine with this timing setting. I have disconnected the vac line to the distributor when setting the timing and it uses ported vac. Any ideas on why I have to set it so far advanced???
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post #2 of 3 (permalink) Old Oct 27th, 03, 02:34 PM
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Matt Jones
Join Date: Jan 2002
Location: Renton, WA USA
Posts: 2,765

The reason why you are getting more vacuum is because the RPMs go up when timing is increased.

I would imaging the engine would run best with about 18 degrees intial (not sure on cam specs, so I'm guessing on that), with 36* at around 2800.

As far as the low idle vacuum goes, is there a leak somewhere? What is your idle RPM?

Matt Jones
Lead Mechanical Engineer
Art Morrison Ent. Inc.
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post #3 of 3 (permalink) Old Oct 28th, 03, 02:07 AM Thread Starter
Join Date: Feb 2003
Posts: 17

Idle RPM is 950. I do not know the cam specs. I have checked for Vaccuum leaks on the top of the manifold. Could I have a vacuum leak between the manifold and the lifter area? How do I check it?
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